Perfluorocyclobutyl-based methacrylate monomers: Synthesis and radical polymerization

Article abstract of DOI:10.1016/j.jfluchem.2008.12.012

A new class of methacrylate monomers containing perfluorocyclobutyl unit was synthesized in multi-steps including crossing-dimerization, demethylation and esterification using commercially available p-substituted phenol, tetrafluoroethylene and methacryloyl chloride as starting materials. These monomers can be polymerized in solution to provide perfluorocyclobutyl-based polymethacrylate, a kind of potential transparent material.

Full text of DOI:10.1016/j.jfluchem.2008.12.012

Journal of Fluorine Chemistry 130 (2009) 354–360
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Perfluorocyclobutyl-based methacrylate monomers: Synthesis and radical
polymerization
a
b
Yongjun Li a,b,c, Sen Zhang b, Liang Tong b, Qingnuan Li a, , Wenxin Li , Guolin Lu ,
*
Hao Liu b, Xiaoyu Huang b,
*
a Laboratory of Nano-Biology and Medicine, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 2019 Jialuo Road, Shanghai 201800, PR China
b Key Laboratory of Organofluorine Chemistry and Laboratory of Polymer Materials, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Road, Shanghai 200032, PR China
c Graduate University of Chinese Academy of Sciences, Beijing 100080, PR China
A R T I C L E I N F O
A B S T R A C T
Article history:
A new class of methacrylate monomers containing perfluorocyclobutyl unit was synthesized in multi-
steps including crossing-dimerization, demethylation and esterification using commercially available p-
substituted phenol, tetrafluoroethylene and methacryloyl chloride as starting materials. These
monomers can be polymerized in solution to provide perfluorocyclobutyl-based polymethacrylate, a
kind of potential transparent material.
Received 26 September 2008
Received in revised form 30 December 2008
Accepted 30 December 2008
Available online 9 January 2009
ß 2009 Elsevier B.V. All rights reserved.
Keywords:
Perfluorocyclobutyl (PFCB)
Methacrylate
Crossing-dimerization
1. Introduction
of copolymers via trifluorovinyl aryl ether monomers and other
commonly used monomers due to the normal high polymerization
Perfluorocyclobutyl (PFCB) aryl ether polymers are a relatively
new class of fluoropolymers developed by the researchers of Dow
Chemical Co. in 1993 [1]. This kind of fluoropolymers is generally
temperature (>150 8C) and unusual polymerization mechanism
without any initiator [10–13]. The number of PFCB linkage in
copolymers was very difficult to be tuned. In addition, none has
reported the introduction of PFCB aryl ether unit into commonly
used monomer, which has certainly limited the application of
PFCB-based fluoropolymers.
synthesized by thermal [2p + 2p] step-growth cyclopolymeriza-
tion of trifluorovinyl aryl ethers at a high temperature between
150 8C and 250 8C in bulk or solution without any initiator or
catalyst. As an emerging class of semi-fluorinated polymers, PFCB-
based polymers provide the conventional properties of fluoropo-
lymer such as low surface energy, high thermal/oxidative stability
and high chemical resistance, also possessing many other
advantages including optical transparency and improved proces-
sability [2–5].
Most recent studies of PFCB-based polymers focused on
thermal polymerization of different fluorinated trifluorovinyl aryl
ether monomers to obtain a variety of homopolymers and random
copolymers containing PFCB linkages [6–9]. Monomers containing
two or three trifluorovinyl ethers were synthesized from different
commercially available polyphenols and were polymerized to
afford different thermoplastic or thermoset PFCB aryl ether
polymers. However, only few literatures reported the synthesis
In order to enlarge its application range, it is necessary to
combine the high performance of PFCB aryl ether polymer with
other commercial polymers. To realize this, incorporation of
PFCB linkage into acrylate/methacrylate monomer via a stable
covalent bond using commercially available (meth)acryloyl
chloride is a good and convenient choice. Thus, well-defined
polymethacrylates bearing pendant PFCB linkages can be
prepared by ‘‘living’’ polymerization of PFCB-based methacry-
late monomers and the number of PFCB linkage can be
controlled by the feed ratio of the monomer to the initiator.
In addition, it is feasible to synthesize well-defined block or graft
copolymers containing PFCB linkages via ‘‘living’’ polymeriza-
tion, which may find potential applications in information
storage, photonic material and stimuli-responsive nanostructure
[14]. Furthermore, as a new method of modifying methacrylate
monomer, the introduction of PFCB linkage may increase the
thermal stability and glass transition temperature (Tg) of the
obtained polymers [15].
* Corresponding authors. Tel.: +86 21 54925310; fax: +86 21 64166128.
E-mail address: xyhuang@mail.sioc.ac.cn (X. Huang).
0022-1139/$ – see front matter ß 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2008.12.012

Y. Li et al. / Journal of Fluorine Chemistry 130 (2009) 354–360
355
Scheme 1. Synthesis of PFCB-containing methacrylate monomer.
In this work, we presented the synthesis of a new class of PFCB-
containing methacrylate monomers via commercially available
reagents (Scheme 1). PFCB linkage was incorporated into
methacrylate monomer as a side group. Radical polymerizations
of these methacrylate monomers can be easily initiated by 2,20-
azobis(isobutyronitrile) to give PFCB-based polymers.
commercially available 4-methoxyphenol. After cross-coupling,
the transformation of methoxyl into phenolic hydroxyl was readily
carried out by treating with boron tribromide [17,18].
It is well-known that thermal [2p + 2p] cyclodimerization of
fluorinated olefins proceed via a biradical mechanism, the single
requirement being the presence of a terminal difluoromethylene
group in the olefin [1,19]. Therefore, three types of crossing-dimer
products would be obtained after the cross-coupling reaction
between p-(trifluorovinyloxy)anisole and substituted p-(trifluor-
ovinyloxy)benzene (Scheme 3).
2. Results and discussion
2.1. Design and synthesis of monomers
While the reactivity of trifluorovinyl was influenced by
electronic effect of the p-substitution group of the benzene ring
[16], the consumption rate of different TFVE monomers may be
different. p-Bromo(trifluorovinyloxy)benzene (A) and p-(trifluor-
ovinyloxy)anisole (B) were heated neat in NMR tubes and the area
ratio of trans (to O) fluorine signal of A (peak b) to B (peak b0) was
measured as a function of time by 19F NMR (Fig. 1). It was found
that p-(trifluorovinyloxy)anisole (B) had a higher consumption
rate due to the strong electron-donating character of OCH3 group.
The distribution percentages of three different dimers with
various feed ratios were determined by HPLC. Pure homo-dimers of
p-bromo(trifluorovinyloxy)benzene and p-(trifluorovinyloxy)ani-
sole were prepared firstly via thermo-cyclodimerization and used
as calibrations (Fig. 2A and C). The mixtures of cross-dimerization
reaction were analyzed by HPLC under the same condition (Fig. 2B)
and the signal of cross-coupling product located between those of
homo-dimers. Relative contents of three dimers were calculated
from the area ratios as summarized in Table 1.
Substituted p-(trifluorovinyloxy)benzene compounds were
firstly prepared by established method in good yield from
commercially available raw materials including 4-bromophenol,
p-cresol, 4-phenylphenol, 4-cumylphenol and 4-methoxyl phenol
[1]. Second, a series of anisoles containing PFCB linkage was
obtained by the cross-coupling reaction between substituted p-
(trifluorovinyloxy)benzene and p-(trifluorovinyloxy)anisole with
reasonable yields. The anisoles were demethylated by BBr3 to give
the corresponding phenols containing PFCB unit. Finally, metha-
cryloyl chloride was used to esterify the phenols to provide the
targeted PFCB-containing methacrylate monomers.
The key step of the synthesis is the preparation of important
intermediate, p-(2-aryloxyperfluorocyclobutoxy)phenol. This kind
of intermediates can be prepared via a cross-coupling reaction using
different starting materials as shown in Scheme 2, p-(trifluorovi-
nyloxy)phenol or p-(trifluorovinyloxy)anisole. The synthesis of p-
(trifluorovinyloxy)phenol has been reported via a boronic acid
intermediate from p-bromo(trifluorovinyloxy)benzene [16]. How-
ever, the relative severe reaction condition confined the preparation
in a large scale. Thus, p-(trifluorovinyloxy)anisole was selected as
starting material since that it can be easily prepared from
It was found that the crossing-dimer (AB) accounted for at least
42% of the dimers under various feed ratios. When the feed ratio of
A to B was 1:1, the percentage of AB crossing-dimer was higher
than others. Due to the higher consumption rate of p-(trifluor-
Scheme 2. Two different strategies to synthesize the intermediate.

356
Y. Li et al. / Journal of Fluorine Chemistry 130 (2009) 354–360
Scheme 3. Crossing-dimerization of p-(trifluorovinyloxy)anisole and substituted p-(trifluorovinyloxy)benzene.
Fig. 1. (A) 19F NMR spectra of p-bromo(trifluorovinyloxy)benzene, p-(trifluorovinyloxy)anisole and their cross-dimerization mixture. (B) Relative consumption rate of p-
bromo(trifluorovinyloxy)benzene to p-(trifluorovinyloxy)-anisole determined by 19F NMR.
ovinyloxy)anisole evidenced by 19F NMR, the feed ratio of A to B
was selected to be 1:1.2 with a slight excess of p-(trifluoroviny-
loxy)anisole in order to raise the yield of crossing-dimer or to
reduce the self-coupling products of substituted p-(trifluoroviny-
loxy)benzene. The mixture of three different dimers was readily
separated by column chromatograph and the isolated yield of
crossing-dimer was higher than 50%.
The structures of desired crossing-dimers were characterized
by 1H NMR, 19F NMR, 13C NMR and EI-MS. Fig. 3A shows 1H NMR
spectrum of crossing-dimer 1b. The signals of the protons of
benzene ring adjacent to –OCH3 and PFCB were found to locate at
6.83 ppm and 7.05 ppm, respectively. The peak of two protons of
benzene ring adjacent to Br appeared at 7.43 ppm. In particular, the
peak at 3.79 ppm was attributed to three protons of –OCH3 and its
Fig. 2. HPLC traces of homo-dimers and cross-dimerization mixture of p-bromo-
(trifluorovinyloxy)benzene and p-(trifluorovinyloxy)anisole.
Fig. 3. 1H NMR spectra of the dimers from the cross-coupling reaction between p-
(trifluorovinyloxy)anisole and p-bromo(trifluorovinyloxy)benzene in CDCl3.

Y. Li et al. / Journal of Fluorine Chemistry 130 (2009) 354–360
357
Table 1
Distribution percentage of dimers with different feed ratios.
Entry
A:B (mole ratio)
Distribution percentage (%)a
AA
AB
BB
1
2
3
1:1
1:2
2:1
14.1
6.3
52.6
42.7
52.2
33.3
51.0
15.9
31.9
a
Determined by HPLC in CH3CN/H2O at 25 8C.
presence can be confirmed from 1H NMR spectra of homo-dimers
derived from p-(trifluorovinyloxy)anisole (Fig. 3B) and p-bromo(-
trifluorovinyloxy)benzene (Fig. 3C).
The demethylation of crossing-dimers firstly proceeded accord-
ing to the method introduced by Morita et al. [20]. However, that
system did not fit our substrates and we did not find any trace of
anticipated product. Therefore, another approach of demethyla-
tion using BBr3 was employed in CH2Cl2 at room temperature
[17,18], which gave PFCB-containing phenols with almost quanti-
tative yields. The esterification of PFCB-containing phenols and
methacryloyl chloride was carried out following previously
reported procedure [21] with a yield about 70%. Chemical structure
of PFCB-containing methacrylate monomers was confirmed by 1H
NMR, 19F NMR, 13C NMR, FT-IR and HRMS.
Fig. 4. FT-IR spectra of 3a (A) and PMePFCBMA (B).
which has been proven to be a useful analytical tool since that this
region is rarely occupied by other functionalities [22].
1H NMR spectrum of polymerized product of 3a clearly showed
the disappearance of vinylidene signals at 5.78 ppm and 6.35 ppm
and the signals of the backbone appeared at 1.37 (CCH3) ppm and
1.47 (CH2) ppm (Fig. 5A). In addition, the existence of PFCB linkage
was also illustrated by the typical multiplets ranging from
ꢀ128.1 ppm to ꢀ133.0 ppm in 19F NMR spectrum (Fig. 5B) of
polymerized product of 3a.
2.2. Radical homopolymerization of PFCB-containing methacrylate
monomer
PFCB-containing methacrylate monomers could be easily
homopolymerized by free radical solution polymerization in
toluene or 2-butanone using some traditional free radical initiators
such as 2,20-azobis(isobutyronitrile) (AIBN) or benzoyl peroxide
(BPO). The details of polymerization conditions, molecular weights
and molecular weight distributions were listed in Table 2.
Fig. 4B shows FT-IR spectrum of polymerized product of 3a, the
signal of C C stretching vibration at 1638 cmꢀ1 disappeared
compared to that of 3a (Fig. 4A). The sharp peak of C O stretching
vibration shifted from 1740 cmꢀ1 to 1752 cmꢀ1 after the poly-
merization due to the disappearance of double bond. A strong
sharp band at 962 cmꢀ1 evidenced the presence of PFCB linkage,
Thermal properties of these homopolymers were measured by
differential scanning calorimetry (DSC) and thermogravimetric
analysis (TGA) as listed in Table 2. The initial decomposition
temperatures (Td) are all higher than 250 8C and the glass
transition temperatures (Tg) are all above 160 8C. These results
demonstrated that the incorporation of PFCB unit indeed increased
the thermal stability and glass transition temperature (Tg) of the
resulting polymers.
Solubility tests were performed for PFCB-based polymethacry-
late in a majority of commonly used organic solvents. This kind of
Table 2
Homopolymerization of PFCB-containing methacrylate monomer 3.
a
a
c
d
Monomer structure
[M]:[I]
55:1
Mn (Da)
Mw/Mn
Nb
Td (8C)
Tg (8C)
53,200
1.81
119
234
160
55:1
49:1
62,200
72,700
1.87
1.91
121
143
259
193
242
266
166
213
42:1
77,900
2.16
141
a
Measured by GPC in THF at 35 8C.
Degree of polymerization.
b
c
Measured by TGA (10 8C/min) in N2.
Measured by DSC (10 8C/min) in N2.
d

358
Y. Li et al. / Journal of Fluorine Chemistry 130 (2009) 354–360
standards and CF3CO2H was used as external standard for 19F NMR.
HPLC measurements were carried out on a PerkinElmer LC200
instrument equipped with a Kromasil C18 column and a Perki-
nElmer 785A UV/vis detector (l = 254 nm) at 25 8C using CH3CN/
H2O as eluent with a flow rate of 1.0 mL/min. Relative molecular
weights and molecular weight distributions were measured by a
Waters gel permeation chromatography (GPC) system equipped
with a Waters 1515 Isocratic HPLC pump, a Waters 2414 refractive
index detector (RI) and a set of Waters Styragel columns (HR3, HR4,
and HR5, 7.8 mm ꢁ 300 mm). GPC measurements were carried out
at 35 8C using tetrahydrofuran (THF) as eluent with a flow rate of
1.0 mL/min. The system was calibrated with linear polystyrene
standards. Differential scanning calorimetry and thermogravimetric
analysis measurements were run on a PerkinElmer Pyris 1 system
under N2 purge with a heating rate of 10 8C/min.
4.3. Preparation of crossing-dimers (1a–d)
4.3.1. 4-(2-(p-Tolyloxy)perfluorocyclobutoxy)anisole (1a)
Fig. 5. 1H NMR and 19F NMR spectra of PMePFCBMA.
p-(Trifluorovinyloxy)toluene (20 mL, 0.13 mol) and p-(trifluor-
ovinyloxy)anisole (25 mL, 0.15 mol) were added to a pre-dried
flask and the mixture was heated at 170 8C for 12 h under N2. The
desired product 1a of a colorless oil was obtained by column
chromatography (hexane: ethyl acetate = 100:1) with a yield of
polymethacrylate is soluble in acetone, dichloromethane, acet-
onitrile, N,N-dimethylformamide, ethyl acetate, tetrahydrofuran,
and toluene; insoluble in dimethyl sulfoxide and hexane. The
results implied these PFCB-based homopolymers have good
processability.
51.6%. 1H NMR:
7.10 (m, 6H). 19F NMR:
F6). 13C NMR:
(ppm): 20.5, 20.6, 55.4, 55.5, 114.5, 114.6, 118.0,
118.4, 119.8, 120.1, 122.9, 130.0, 130.1, 134.7, 135.0, 145.9, 146.2,
150.3, 150.5, 156.9, 157.1, 157.9. FT-IR (KBr):
(cmꢀ1): 2956, 2860,
d
(ppm): 2.32 (s, 3H), 3.78 (d, 3H), 6.86 (dd, 2H),
(ppm): ꢀ128.6 to ꢀ131.81 (m, cyclobutyl-
d
d
3. Conclusion
n
In summary, we have developed an efficient strategy for
1507, 1193, 962 (PFCB). EI-MS: m/z 392. HRMS: C18H14O3F6, calcd.
synthesis of
a
new family of PFCB-containing methacrylate
392.0847, found 392.0865.
monomers from commercially available phenols and tetrafluor-
oethylene. p-(2-Aryloxyperfluorocyclobutoxy)anisole was prepared
by the cross-coupling reaction between p-(trifluorovinyloxy)anisole
and substituted p-(trifluorovinyloxy)benzene followed by the
almost quantitative removing of methyl. PFCB-containing metha-
crylate monomers were synthesized by the esterification of p-(2-
aryloxyperfluorocyclobutoxy)phenol with methacryloyl chloride.
They can be readily polymerized using common AIBN or BPO as free
radical initiators. The excellent solubility of the homopolymers in
conventional solvents indicated improved processability.
4.3.2. 4-(2-(p-Bromophenoxy)perfluorocyclobutoxy)anisole (1b)
The product is a colorless oil with a yield of 54.4%. 1H NMR:
(ppm): 3.79 (d, 3H), 6.83 (dd, 2H), 7.05 (m, 4H), 7.43 (dd, 2H). 19
d
F
d
NMR:
d
(ppm): ꢀ129.2 to ꢀ132.5 (m, cyclobutyl-F6). 13C NMR:
(ppm): 55.3, 114.5, 119.6, 119.8, 119.9, 120.3, 120.4, 122.9, 132.6,
132.7, 145.7, 146.0, 151.5, 151.7, 157.1, 157.3. FT-IR (KBr):
(cmꢀ1): 2956, 2839, 1506, 1486, 1197, 962 (PFCB). EI-MS: m/z 456.
HRMS: C17H11O3F6Br, calcd. 455.9796, found 455.9786.
n
4.3.3. 4-(2-(p-Phenylphenoxy)perfluorocyclobutoxy)anisole (1c)
4. Experimental
The product is a white crystal with a yield of 56.5%. 1H NMR:
d
(ppm) 3.76 (d, 3H), 6.84 (q, 2H), 7.12 (t, 2H), 7.25 (q, 2H), 7.36 (d,
1H), 7.42 (t, 2H), 7.53 (m, 4H). 19F NMR:
(ppm): ꢀ128.6 to ꢀ132.1
(m, cyclobutyl-F6). 13C NMR:
(ppm): 55.5, 114.5, 114.6, 118.4,
118.7, 119.7, 120.2, 126.9, 127.4, 128.2, 128.3, 128.8, 138.4, 139.9,
145.9, 151.8, 157.1. FT-IR (KBr):
(cmꢀ1): 2961, 2838, 1605, 1506,
4.1. Materials
d
d
2,20-Azobis(isobutyronitrile) (Aldrich, 98%) was recrystallized
from anhydrous ethanol. Granular zinc was activated by washing
in 0.1 N HCl followed by drying at 140 8C in vacuo for 10 h. 1,2-
Dibromotetrafluoroethane was prepared by condensing equimolar
amounts of Br2 and tetrafluoroethylene at ꢀ195 8C followed by
warming up to 22 8C [23]. All solvents were purified by standard
methods prior to use. 4-Methoxyphenol (Aldrich, 99%), p-cresol
(Aldrich, 98%), 4-bromophenol (Aldrich, 99%), 4-cumylphenol
(Aldrich, 99%), 4-phenylphenol (Aldrich, 97%), methacryloyl
chloride (Alfa Aesar, 97%) and boron tribromide (BBr3, Alfa Aesar,
99%) were used as received
n
1481, 1184, 961 (PFCB), 763. EI-MS: m/z 454. HRMS: C23H16O3F6,
calcd. 454.1004, found 454.1001.
4.3.4. 4-(2-(p-Cumylphenoxy)perfluorocyclobutoxy)anisole (1d)
The product is a colorless oil with a yield of 67.9%. 1H NMR:
d
(ppm): 1.75 (s, 6H), 3.83 (s, 3H), 6.93 (d, 2H), 7.29 (m, 11H). 19F
NMR:
d
(ppm): ꢀ128.3 to ꢀ132.2 (m, cyclobutyl-F6). 13C NMR:
d
(ppm): 30.7, 42.5, 42.6, 55.5, 114.5, 114.6, 117.5, 117.6, 119.8,
120.0, 125.8, 126.7, 128.0, 128.1, 145.9, 146.2, 147.5, 147.8, 150.2,
150.4, 156.8, 157.0. FT-IR (KBr):
n
(cmꢀ1): 2970, 2839, 1602, 1506,
4.2. Measurements
1202, 1184, 962 (PFCB), 763. EI-MS: m/z 496. HRMS: C26H22O3F6,
calcd. 496.1473, found 496.1468.
FT-IR spectra were recorded on a Nicolet AVATAR-360 FT-IR
spectrophotometer with
a
resolution of 4 cmꢀ1
.
EI-MS was
4.4. Demethylation of crossing-dimers by BBr3
measured by an Agilent 5937N system. HRMS was recorded on a
Waters Micromass GCT instrument. All NMR analyses were
performed on a Bruker Avance 500 spectrometer (500 MHz) in
(
CDCl3, TMS (1H NMR) and CDCl3 13C NMR) were used as internal
4.4.1. 4-(2-(p-Tolyloxy)perfluorocyclobutoxy)phenol (2a)
To a solution of 1a (13.67 g, 0.035 mol) in CH2Cl2 (240 mL), BBr3
(1 M in CH2Cl2, 70 mL, 0.07 mol) was added dropwise at 0 8C for 1 h.

Y. Li et al. / Journal of Fluorine Chemistry 130 (2009) 354–360
359
Themixturewaswarmedtoroomtemperatureandstirredovernight.
2H) 7.25 (d, 2H), 7.35 (t, 1H), 7.44 (t, 2H), 7.53 (d, 4H).19F NMR:
d
Water (50 mL) was added to terminate the reaction followed by
adding 1 N NaOH (100 mL). The mixture was extracted with ethyl
acetate and the extracts were washed with saturated NaHCO3 and
brine, dried over Na2SO4. After concentration, the desired product 2a
of a light brown oil was obtained by flash chromatography (hexane:
(ppm): ꢀ128.2 to ꢀ132.3 (m, cyclobutyl-F6). 13C NMR:
d
(ppm):
18.2, 118.2, 118.7, 119.1, 119.5, 122.7, 126.9, 127.3, 127.4, 128.2,
128.3, 128.7, 135.5, 138.2, 138.5, 139.8, 147.7, 148.0, 149.6, 149.8,
151.7, 151.8, 165.5. FT-IR (KBr):
n
(cmꢀ1): 3060, 3035, 2930, 1739
(C O), 1638, 1503, 1483, 1318, 1202, 1124, 962 (PFCB). EI-MS: m/z
508. HRMS: C21H16O4F6, calcd. 508.1109, found 508.1094.
ethylacetate = 10:1)withaquantitativeyield.1HNMR:
d
(ppm):2.32
(ppm):
(s, 3H), 5.30 (s, 1H), 6.79 (dd, 2H), 7.08 (m, 6H). 19F NMR:
d
ꢀ128.6 to ꢀ131.8 (m, cyclobutyl-F6). EI-MS: m/z 378.
4.5.4. 4-(2-(p-Cumylphenyloxy)perfluorocyclobutoxy)phenyl
methacrylate (3d)
4.4.2. 4-(2-(p-Bromophenoxy)perfluorocyclobutoxy)phenol (2b)
The product is a colorless oil with a yield of 64.3%. 1H NMR:
d
The product is a light brown oil with a quantitative yield. 1H
(ppm): 1.66 (s, 6H), 2.05 (s, 3H), 5.76 (s, 1H), 6.34 (s, 1H), 7.00 (dd,
NMR:
d
(ppm): 5.30 (s, 1H), 6.79 (dd, 2H), 7.02 (m, 4H), 7.42 (dd,
2H), 7.07 (m, 4H), 7.19 (m, 7H). 19F NMR:
d
(ppm): ꢀ128.2 to
2H). 19F NMR:
d
(ppm): ꢀ128.3 to ꢀ132.5 (m, cyclobutyl-F6). EI-
ꢀ132.3 (m, cyclobutyl-F6). 13C NMR:
d (ppm): 18.2, 30.6, 42.5,
MS: m/z 442.
117.4, 117.7, 119.1, 119.4, 122.7, 122.8, 125.7, 126.6, 127.4, 128.0,
128.1, 135.6, 147.6, 147.8, 147.9, 148.0, 149.7, 150.1, 150.3, 165.5.
FT-IR (KBr): n
(cmꢀ1): 3059, 3024, 2970, 1740 (C O), 1638, 1503,
4.4.3. 4-(2-(p-Phenylphenoxy)perfluorocyclobutoxy)phenol (2c)
The product is a light brown crystal with a quantitative yield. 1H
1318, 1202, 1124, 963 (PFCB). EI-MS: m/z 550. HRMS: C21H16O4F6,
NMR:
d
(ppm): 5.30 (s, 1H), 6.77 (dd, 2H), 7.06 (t, 2H), 7.20 (t, 2H),
calcd. 550.1579, found 550.1580.
7.35 (t, 1H), 7.44 (t, 2H), 7.54 (m, 4H). 19F NMR:
d
(ppm): ꢀ128.6 to
ꢀ132.0 (m, cyclobutyl-F6). EI-MS: m/z 440.
4.6. Radical homopolymerization of PFCB-containing methacrylate
monomers
4.4.4. 4-(2-(p-Cumylphenoxy)perfluorocyclobutoxy)phenol (2d)
The product is a light brown oil with a quantitative yield. 1H
4.6.1. General procedure
NMR:
d
(ppm): 1.72 (s, 6H), 5.30 (s, 1H), 6.80 (dd, 2H), 7.09 (m, 4H),
To a 10 mL Schlenk flask (flame-dried under vacuum prior to
use) sealed with a rubber septum, certain amounts of PFCB-
containing methacrylate monomer 3, AIBN and 2-butanone (1 mL)
were charged followed by three cycles of freeze-pump-thaw. The
flask was immersed into an oil bath preset at 70 8C. The
homopolymerization lasted for 8 h and the homopolymer was
precipitated into excess methanol. The raw product was purified
by dissolving in THF and precipitating into methanol for three
times, a white solid was obtained after drying in vacuo at 50 8C for
24 h.
7.23 (m, 7H),. 19F NMR:
d
(ppm): ꢀ128.5 to ꢀ132.1 (m, cyclobutyl-
F6). EI-MS: m/z 482.
4.5. Synthesis of PFCB-containing methacrylate monomers (3a–d)
4.5.1. 4-(2-(p-Tolyloxy)perfluorocyclobutoxy)phenyl methacrylate
(3a)
2a (3.0 g, 0.008 mol) and triethylamine (0.93 mL, 0.0096 mol)
were dissolved in 25 mL of 2-butanone and the mixture was stirred
at 0–5 8C. Methacryloyl chloride (1.4 mL, 0.0096 mol) in 10 mL of
2-butanone was added dropwise for 30 min and the mixture was
stirred for another 1 h. Finally, the mixture was stirred at room
temperature for 1 h. The precipitated triethylammonium chloride
was filtered and the filtrate was washed twice with water. The
solution was dried over Na2SO4 followed by the concentration to
remove 2-butanone. The desired product 3a of a colorless oil was
obtained by flash column chromatograph (hexane: ethyl acet-
Poly(4-(2-(p-tolyloxy)perfluorocyclobutoxy)phenyl methacry-
late): 1H NMR:
d
(ppm): 1.36 (3H, CCH3), 1.47 (2H, CH2), 2.25 (3H,
C6H4CH3), 6.97, 7.04 (8H, phenyl). 19F NMR:
(ppm): ꢀ128.1 to
ꢀ133.0 (m, cyclobutyl-F6). FT-IR (KBr):
(cmꢀ1): 2929, 1752
(C O), 1503, 1317, 1178, 1104, 962 (PFCB).
Poly(4-(2-(p-bromophenoxy)perfluorocyclobutoxy)phenyl
methacrylate): 1H NMR:
(ppm): 1.38 (3H, CCH3), 1.48 (2H, CH2),
7.00, 7.38 (8H, phenyl). 19F NMR:
(ppm): ꢀ128.1 to ꢀ132.0 (m,
cyclobutyl-F6). FT-IR (KBr):
(cmꢀ1): 2956, 1752 (C O), 1502,
1314, 1200, 1103, 962 (PFCB).
Poly(4-(2-(p-phenylphenyloxy)perfluorocyclobutoxy)phenyl
methacrylate): 1H NMR:
(ppm): 1.35 (3H, CCH3), 1.45 (2H, CH2),
6.97, 7.09, 7.33, 7.43 (13H, phenyl). 19F NMR:
(ppm): ꢀ127.9 to
ꢀ132.7 (m, cyclobutyl-F6). FT-IR (KBr):
(cmꢀ1): 2930, 1751
(C O), 1502, 1314, 1201, 1104, 962 (PFCB).
Poly(4-(2-(p-cumylphenyloxy)perfluorocyclobutoxy)phenyl
methacrylate): 1H NMR:
(ppm): 1.37 (3H, CCH3), 1.48 (2H, CH2),
1.59 (6H, C6H5C(CH3)2), 7.00, 7.13 (13H, phenyl). 19F NMR:
d
n
d
d
ate = 100:1) with a yield of 87.0%. 1H NMR:
d
(ppm): 2.06 (s, 3H),
n
2.32 (s, 3H), 5.78 (s, 1H), 6.35 (s, 1H), 7.12 (m, 8H). 19F NMR:
d
(ppm): ꢀ128.4 to ꢀ132.4 (m, cyclobutyl-F6). 13C NMR:
d (ppm):
18.3, 20.6, 117.8, 117.9, 119.2, 119.5, 121.2, 122.7, 122.8, 126.9,
127.4, 129.9, 130.1, 130.2, 134.8, 135.3, 136.0, 147.8, 148.0, 148.7,
d
d
149.7, 149.9, 150.2, 165.6. FT-IR (KBr):
1638, 1503, 1319, 1187, 1123, 963 (PFCB), 817. EI-MS: m/z 446.
HRMS: C21H16O4F6, calcd. 446.0953, found 446.0964.
n
(cmꢀ1): 2930, 1740 (C O),
n
d
4.5.2. 4-(2-(p-Bromophenoxy)perfluorocyclobutoxy)phenyl
d
methacrylate (3b)
(ppm): ꢀ127.7 to ꢀ133.0 (m, cyclobutyl-F6). FT-IR (KBr):
n
(cmꢀ1):
The product is a colorless oil with a yield of 75.6%. 1H NMR:
d
2970, 1752 (C O), 1502, 1317, 1202, 1105, 963 (PFCB).
(ppm): 1.98 (s, 3H), 5.69 (s, 1H), 6.27 (s, 1H), 7.04 (m, 6H), 7.37 (dd,
2H). 19F NMR:
NMR:
d
(ppm): ꢀ128.3 to ꢀ132.1 (m, cyclobutyl-F6). 13C
Acknowledgements
d
(ppm): 18.0, 118.9, 119.5, 119.7, 120.2, 122.5, 122.6, 127.3,
132.6, 132.7, 135.5, 147.9, 148.2, 149.4, 149.6, 151.3, 151.4, 165.3,
165.4. FT-IR (KBr):
(cmꢀ1): 3106, 2963, 2931, 1740 (C O), 1638,
1503, 1486, 1317, 1202, 1124, 963 (PFCB), 825. EI-MS: m/z 510.
The authors thank the financial support from National Natural
Science Foundation of China (20674094 and 10775169), Ministry
of Science and Technology of ‘‘National High Technology Research
and Development Program’’ (2006AA03Z541).
n
HRMS: C21H16O4F6, calcd. 509.9901, found 509.9902.
4.5.3. 4-(2-(p-Phenylphenyloxy)perfluorocyclobutoxy)phenyl
References
methacrylate (3c)
The product is a white crystal with a yield of 68.2%. 1H NMR:
d
[1] D.A. Babb, B.R. Ezzell, K.S. Clement, W.F. Richey, A.P. Kennedy, J. Polym. Sci. Polym.
Chem. 31 (1993) 3465–3477.
(ppm): 2.04 (s, 3H), 5.76 (s, 1H), 6.32 (s, 1H), 7.10 (d, 2H), 7.19 (d,

360
Y. Li et al. / Journal of Fluorine Chemistry 130 (2009) 354–360
[11] X.Y. Huang, G.L. Lu, D. Peng, S. Zhang, F.L. Qing, Macromolecules 38 (2005) 7299–
[2] A.E. Feiring, in: R.E. Banks, B.E. Smart, J.C. Tatlow (Eds.), Organofluorine Chem-
istry: Principle and Commercial Applications, Plenum Press, New York, 1994, pp.
339–371.
[3] M. Yamabe, in: R.E. Banks, B.E. Smart, J.C. Tatlow (Eds.), Organofluorine Chem-
istry: Principle and Commercial Applications, Plenum Press, New York, 1994, pp.
397–402.
[4] P.R. Resnick, W.H. Buck, in: J. Schirs (Ed.), Modern Fluoropolymers: High Perfor-
mance Polymers for Diverse Applications, Wiley, New York, 1997, pp. 397–420.
[5] S.T. Iacono, S.M. Budy, J.Y. Jin, D.W. Smith, J. Polym. Sci. Polym. Chem. 45 (2007)
5705–5721, and references therein.
[6] X.Z. Jiang, S. Liu, M.S. Liu, P. Herguth, A.K.Y. Jen, H. Fong, M. Sarikaya, Adv. Funct.
Mater. 12 (2002) 745–751.
7305.
[12] G.L. Lu, S. Zhang, X.Y. Huang, J. Polym. Sci. Polym. Chem. 44 (2006) 5438–5444.
[13] Y.Q. Zhu, Y.G. Huang, W.D. Meng, H.Q. Li, F.L. Qing, Polymer 47 (2006) 6272–
6279.
[14] C. Park, J. Yoon, E.L. Thomas, Polymer 44 (2003) 6725–6760.
[15] A.A. Kavitha, N.K. Singha, J. Polym. Sci. Polym. Chem. 46 (2008) 7101–7113.
[16] B.K. Spraul, S. Suresh, J.Y. Jin, D.W. Smith, J. Am. Chem. Soc. 128 (2006) 7055–
7064.
[17] J. Storch, J. Cermak, J. Karban, Tetrahedron Lett. 48 (2007) 6814–6816.
[18] H.Y. Lee, J.Y. Oh, H.Y. Chu, J.I. Lee, S.H. Kim, Y.S. Yang, G.H. Kim, L.M. Do, T. Zyung, J.
Lee, Y. Park, Tetrahedron 59 (2003) 2773–2779.
[7] D.W. Smith, D.A. Babb, H.V. Shah, A. Hoeglund, R. Traiphol, D. Perahia, H.W.
Boome, C. Langhoff, M. Radler, J. Fluorine Chem. 104 (2000) 109–117.
[8] S.Y. Cho, H.R. Allcock, Chem. Mater. 19 (2007) 6338–6344.
[9] V.E. Campbell, P. Paoprasert, J.D. Mykietyn, I. In, D.J. McGee, P. Gopalan, J. Polym.
Sci. Polym. Chem. 45 (2007) 3166–3177.
[19] I. Wlassics, J. Fluorine Chem. 125 (2004) 1519–1528.
[20] T. Morita, Y. Okamoto, H. Sakurai, J. Chem. Soc. Chem. Commun. (1978) 874–875.
[21] M.V. Patel, J.N. Patel, A. Ray, R.M. Patel, J. Polym. Sci. Polym. Chem. 43 (2005)
157–167.
[22] D.W. Smith, D.A. Babb, Macromolecules 29 (1996) 852–860.
[23] Y. Kastsuhara, D.D. DesMarteau, J. Am. Chem. Soc. 102 (1980) 2681–2686.
[10] R. Souzy, B. Ameduri, B. Boutevin, Prog. Polym. Sci. 29 (2004) 75–106.